This invention relates to conveying devices, and in particular to a recirculating apparatus for transfer of objects from a first position to a second position, with the transferring means being rotationally stationary and not rotating about its own axis as the apparatus recirculates.
Recirculating apparatus for conveying objects from one location to another is well known. For example, a simple conveyor belt, which is endlessly recirculating, can transfer objects from an inlet location to an outlet location. More sophisticated conveying devices, such as belts having segmented flights or dividers, accomplish the same purpose. However, because the conveyor rotates about opposite sprockets or wheels on opposite ends of the conveyor, any upstanding flights or dividers, particularly those extending some distance from the surface of the conveyor belt, accelerate as motion changes from linear to circular as the flights or dividers are returned in their endless paths. When a conveyor is used to push or lift an object, such acceleration can be particularly undesirable if constant velocity of the object is desired. The assignee of the present application, Hayssen Manufacturing Company of Sheboygan, Wis., U.S.A., manufactures packaging equipment in which conveyor flights are used to transfer packages or portions of packages from one location to another. For precise timing and proper handling of the packages, it is imperative that conveyors not accelerate the packages unless acceleration is an intended result. Thus, when packages are pushed or lifted by flights of conveyors, it is important that as the packages are either disengaged or engaged by the flights, the flights maintain a constant velocity at all locations of engagement with a conveyed package. Not only does maintaining a constant velocity properly sequence packages that are conveyed as they pass from one section of an apparatus to another, but also the constant velocity avoids damage to packages as flights are initially brought into contact with packages, or disengage from packages during the return sequence of the flights.
Recognizing that pushing or lifting flights must engage and disengage their transported packages normally at constant velocities, Hayssen Manufacturing Company developed, in the past, a conveying apparatus comprising spaced conveying chains, one of which is offset vertically from the other. Conveying flights are connected horizontally between the chains, with a vertical arm connecting each of the flights to one of the chains. Because the chains are offset from one another, even though the flights travel through a recirculating endless motion, the flights do not rotate about their axes. Therefore, the flights engage and disengage packages at a constant velocity.
A significant problem with such an apparatus, however, has been the fact that the two offset chains must be separated from one another a significant distance in order to accommodate the products being conveyed. The distances between the chains can often be on the order of a foot (1/3 meter) or more. Because the chains are offset from one another, and due to the distances involved, a considerable amount of wracking can occur for a flight, particularly when relatively heavy objects are to be transported. Wracking results in undesired flexibility of the flights, resulting in acceleration or deceleration of conveyed product that was intended to be avoided.